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Health Studies

The most up-to-date research on food, nutrition and healthy lifestyle. Oldways’ health studies database contains hundreds of peer-reviewed studies showing the links between traditional diets and good health. Filters let you ﬁnd just the data you need to support your work.

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Mediterranean and Vegetarian Diets Can Improve Cholesterol in People with Type 2 Diabetes

Poor cholesterol is a risk factor for heart disease, but dietary approaches can be used to keep cholesterol in check. In this review, researchers analyzed 52 randomized controlled trials (the “gold standard” of nutrition research) encompassing 5,360 people with type 2 diabetes, to determine the relationship between diet and cholesterol. They found that vegetarian diets most eﬀectively reduced LDL (“bad”) cholesterol compared with control diets, and that the Mediterranean diet was the overall most eﬀective diet to treat poor cholesterol, raising HDL (“good”) cholesterol and lowering triglycerides (a type of fat in the blood that is a risk factor for heart disease when elevated).European Journal of Epidemiology. 2019 Jun 14. doi: 10.1007/s10654-019-00534-1. [Epub ahead of print] (Neuenschwander M et al.)

Meatless Meals Linked with Lower "Bad" Cholesterol

High cholesterol is a risk factor for heart disease, and it can be easily impacted by food choices. In this study, researchers randomly assigned more than 100 adults to a high saturated fat diet (with lots of butter and fatty dairy) that was meatless, chicken-based, or red meat-based, or a low saturated fat diet (with lowfat dairy) that was meatless, chicken-based, or red meat-based. In both groups, people followed each variation (meatless, chicken-based, or red meat-based) for 4 weeks each, in a random order. Regardless of the protein source, those in the higher saturated fat diet groups had signiﬁcantly higher levels of total cholesterol and “bad” (LDL) cholesterol. Additionally, those in the meatless group (who got their protein from soy, eggs, legumes, nuts, and dairy) had signiﬁcantly lower “bad” (LDL) cholesterol than those in the chicken or red meat groups, with no signiﬁcant diﬀerences observed between chicken and red meat on cholesterol.American Journal of Clinical Nutrition. 2019 Jun 4. pii: nqz035. doi: 10.1093/ajcn/nqz035. [Epub ahead of print] (Bergeron N et al.)

Whole Grains Linked with Healthy Aging

Longevity is fascinating to study, but what is perhaps more important than the years in your life is the life in your years – the ability to age successfully from a medical, social, and lifestyle point of view. In this study, researchers evaluated whole grain intake and measured “successful aging” (using social, lifestyle, and medical indicators) in a group of 3,349 adults ages 50+. Those eating the most whole grains (about 7 servings per day) were signiﬁcantly more likely to score higher on the “successful aging index” than those eating the least whole grains (about 1.5 servings per day). Those eating the most whole grains were also less likely to have high blood pressure, diabetes, and high cholesterol.Nutrients. 2019 May 29;11(6). pii: E1221. doi: 10.3390/nu11061221. (Foscolou A et al.)

More Exposure to Nutritious, Bitter Staples of Med Diet May Improve Consumer Acceptability

Many bitter foods, such as green vegetables, contain a wealth of antioxidants and essential vitamins and minerals. In this review, scientists analyzed existing research on consumer opinions of two bitter-tasting, healthful essentials of the Mediterranean diet: extra virgin olive oil and brassicaceae vegetables (the family of vegetables that includes broccoli and arugula). They found the most important factor in inﬂuencing someone’s perception of these bitter foods is exposure, meaning the more often someone tries these foods, the more likely they’ll be to like them. They also note that music and certain food pairings can make these bitter foods appear to taste less bitter to consumers. In certain demographics (women and elderly consumers), promoting the healthfulness of these bitter foods can also improve acceptability.Nutrients. 2019 May 24;11(5). pii: E1164. doi: 10.3390/nu11051164. (Cavallo C et al.)

Healthy diets are known to support brain health in a general population, so researchers wonder if this beneﬁt also extends to patients with diabetes. Scientists analyzed the eating habits, blood sugar control, and brain function in 913 adults, nearly half of whom had type 2 diabetes. In patients who had good blood sugar control, those most closely following a Mediterranean diet signiﬁcantly improved their cognitive function over the 2-year study. However, the results were not statistically signiﬁcant in patients without diabetes or patients with poor blood sugar control.Diabetes Care. 2019 May 23. pii: dc190130. doi: 10.2337/dc19-0130. [Epub ahead of print] (Mattei J et al.)

Poor Diet Linked with 1/3 of All New Colorectal Cancer Cases

Eating a healthy diet can help protect our health from a number of conditions and complications, so researchers wonder how diet might relate to cancer risk. In this study, researchers used models and dietary data to analyze the cancer cases from 2015. They found that 5.2% of all new cancer cases in 2015 could be attributed to poor diet, with 1.8% attributable to low whole grain consumption, 1.2% attributable to low dairy consumption, and 1% attributable to processed meats. The link with colorectal cancer shows the strongest relationship with diet, as poor diet is linked with 38.3% of all new colorectal cancer cases.JNCI Cancer Spectrum. 2019 May 22;3(2):pkz034. doi: 10.1093/jncics/pkz034. (Zhang FF et al.)

Mediterranean Diet Linked with Longevity

The Mediterranean diet has been associated with longevity since its discovery, so researchers wanted to see if newly-published studies ﬁnd the same association. In this review, researchers analyzed 29 prospective studies following more than 1.6 million people over several years, and they found that each 2-point increase in Mediterranean Diet adherence was linked with a 10% lower risk of death over the study period, and that this relationship was even stronger in people who lived in the Mediterranean.Advances in Nutrition. 2019 May 21. pii: nmz041. doi: 10.1093/advances/nmz041. (Soltani S et al.)

Mediterranean Diet Linked with Lower Risk of Diagnosed Depression

Good food is one of life’s greatest pleasures, and emerging research suggests that certain food choices might ward oﬀ depression as well. Researchers analyzed the diets and mental health of 154 older adults in Greece, to see how a Mediterranean diet might relate to depression. Eating a Mediterranean diet was not linked with a change in risk of depressive symptoms. However, those most closely following a Mediterranean diet were signiﬁcantly less likely to be diagnosed with depression. When looking at individual foods, eating more vegetables, more poultry, and less alcohol was also linked with a lower risk of depression. (Note that ﬁndings presented at meetings are considered preliminary until published in a peer-reviewed journal.)Presentation at American Psychiatric Association Annual Meeting. San Francisco, CA. May 19, 2019

Minimally Processed & Unprocessed Foods Linked with Weight Loss

Many ultra-processed convenience foods are designed to keep us coming back for more. In this study, researchers randomly assigned 20 adults to a diet of ultra-processed foods (packaged pastries, chicken nuggets, American cheese, deli meats, ﬂavored fruit drinks, etc.) or unprocessed foods (spinach, nuts, fruit, chicken breast, plain Greek yogurt, avocado, sweet potato, bulgur, farro, etc.) for 2 weeks, immediately followed by the other diet for the next 2 weeks. The meals on both diets had the same number of calories, carbohydrates, fat, protein, sugar, sodium, and ﬁber, but participants could choose to eat as much or as little of the food that they wanted. People tended to eat 500 more calories on the ultra-processed diet, and gained about 2 pounds, while people tended to lose 2 pounds on the unprocessed diet. The categorization of ultra-processed vs unprocessed/minimally-processed is based on the NOVA system of food classiﬁcation. While there are some concerns about the classiﬁcations used in the NOVA system (such as white rice and white ﬂour being included in the “minimally processed” category alongside intact whole grains), helping direct consumers towards more wholesome, minimally-processed foods may be one strategy to address overeating and associated weight gain.Cell Metabolism. 2019 May 16. pii: S1550-4131(19)30248-7. doi: 10.1016/j.cmet.2019.05.008. (Hall KD et al.)

Following Mediterranean Diet During Pregnancy Linked with Healthy Outcomes for Mothers and Children

Pregnant mothers have a special opportunity to impact not only their own health, but the health of their babies as well, and researchers wonder what some of the short-term and long-term impacts of maternal diet might be. In this article, researchers analyzed 22 studies of pregnant mothers following a Mediterranean diet. They found that, compared with children of mothers who aren’t following a Mediterranean diet, children of mothers who follow a Mediterranean diet during pregnancy are signiﬁcantly less likely to have depressive behaviors or aggression, and are signiﬁcantly less likely to have birth defects (such as dangerous heart defects). Allergic disorders (including eczema and asthma) are less likely in children when mothers follow a Mediterranean diet during pregnancy, and an even stronger association is found when children continue with a Mediterranean diet. The researchers also found beneﬁts for the mothers themselves, as those following a Mediterranean diet during pregnancy were less likely to develop diabetes during pregnancy.Nutrients. 2019 May 17;11(5). pii: E1098. doi: 10.3390/nu11051098. (Amati F et al.)

Acculturation from South Asian Lifestyle to Western Lifestyle Linked with Heart Disease Risk

Around the world, transitioning from a traditional diet with daily movement to a sedentary Western diet is linked with rising rates of chronic disease. In this study, researchers investigated the lifestyle factors that are associated with heart disease risk in South Asian adults. They found that moving from a traditional diet and lifestyle to one low in fruits and vegetables, low in physical activity, and high in alcohol and smoking is linked with a 2 to 3-fold higher risk of incident heart disease. “There’s a high recidivism in subjects who are placed on an eating plan diﬀerent from their usual dietary patterns,” said Dr. Sikand, emphasizing the importance of culturally tailored diets. (Note that ﬁndings presented at meetings are considered preliminary until published in a peer-reviewed journal.)Presentation at National Lipid Association Scientiﬁc Sessions. Miami, FL. May 16, 2019. (Sikand G)

High Fat Mediterranean Diet Good for Weight Loss and Waistline

Although it is still widely feared that high fat diets could lead to weight gain, high fat Mediterranean style diets are actually a helpful tool for weight loss. Using data from the republished PREDIMED study (where adults at risk of heart disease were randomly assigned to a low fat diet, a Mediterranean diet with nuts, or a Mediterranean diet with olive oil for nearly 5 years), scientists analyzed the waist circumference and weight of the participants at baseline and again at the end of the study. While all 3,985 participants with follow up data increased their waist size slightly with aging – even as they lost weight – the Mediterranean diet groups had signiﬁcantly smaller increases in their waistline compared to the low fat control group. Similarly, the Mediterranean diet with olive oil group lost signiﬁcantly more weight than the low fat group, at nearly 1 pound more, but the greater weight loss seen in the nut group was not statistically signiﬁcant. The scientists conclude that “the fear of weight gain from high-fat foods need no longer be an obstacle to adherence to a dietary pattern such as the Mediterranean diet,” and that these results “lend support to not restricting intake of healthy fats in advice for bodyweight maintenance and overall cardiometabolic health.”The Lancet Diabetes and Endocrinology. 2019 May. [Epub ahead of print] (Estruch R et al.)